To make mayonnaise: In a blender or food processor, combine egg yolk, Dijon mustard, and lemon juice. With the machine running, slowly add grapeseed oil about 1 tablespoon at a time; the mixture will become very thick. Remove mixture from machine; stir in herbs and season with salt and pepper. Refrigerate until ready to use (mayonnaise can be made several hours in advance).

To make calamari: Preheat oven to 175°. Line a baking sheet with layers of paper towels and set aside. In a deep frying pan, add 2 inches of grapeseed oil. Heat over high heat until very hot but not smoking (when a pinch of flour is added, it should sizzle). Meanwhile, in a large plastic bag, combine flour, salt, pepper, and coriander. Place about 1/3 of calamari in flour mixture and shake well. Remove calamari from bag, shaking off as much extra flour as possible. Add flour-dusted calamari to pan and fry, turning occasionally, until light golden in color, about 4 minutes. Using a slotted spoon, place cooked calamari onto prepared baking sheet and place in oven to keep warm while preparing remaining batches of calamari. Remove all from oven when done.

Place lemon slices into flour mixture, then shake off excess flour. Fry slices until just golden brown, about 3 minutes.

Transfer calamari and lemon rounds to a platter and serve with mayonnaise.